I don't do very much trimming and pruning work (primary work is mowing), but have a customer wanting me to do things I don't think are appropriate. This customer has potential for much work (already did much work in the Spring - 26 hours worth, and more work recently). I want to have some authoritative source that I can use to help make my recommendations (or rejection of her decisions) on what should be cut when. The most important issue now is timing. I think I can do pretty well on technique (probably have fooled myself here too!), but the the timing issue is important. She wants some things cut NOW, and I don't think NOW is the right time, or best time.

After 12 years of moving into a new home (very large, much landscaping work), she claimed never to have found a contractor who will do a "complete" job for her. Some come, work a day, leave and never return -- too big of job, too difficult. If I can do a good job for her (she was very pleased in early spring), I can have much work. But, I want to do the work right.

Any suggestions beyond the comments in the thread I already found. I am in SW PA, so a book devoted to desert plants does me no good, nor one devoted to tropical plants is no good either.

A book is not going to be your best source of information. Education and experience will be your best resource. If you do not have the time to gain those before you must give your client an answer, network. Find a certified arborist in your area and either pay them for a consultation or sub them the pruning work until you fell confident in your abilities. A certified arborist will be able to identify problems and recommend the best course of action. If you are unable to contact an arborist, perhaps you are aware of someone locally that is educated and experienced in the type of pruning you have questions on and can act as your expert.